Nucleic acid mediated electron transfer

Abstract

The present invention provides for the selective covalent modification of nucleic acids with redox active moieties such as transition metal complexes. Electron donor and electron acceptor moieties are covalently bound to the ribose-phosphate backbone of a nucleic acid at predetermined positions. The resulting complexes represent a series of new derivatives that are bimolecular templates capable of transferring electrons over very large distances at extremely fast rates. These complexes possess unique structural features which enable the use of an entirely new class of bioconductors and photoactive probes.

What is claimed is: 
     
       1. A composition comprising a first single stranded nucleic acid containing one or multiple electron transfer moieties and a second single stranded nucleic acid containing one or multiple electron transfer moieties, wherein said electron transfer moieties are transition metal complexes covalently linked to a ribose of the ribose-phosphate backbone of said first and second single stranded nucleic acids, and wherein electron transfer occurs between said electron transfer moieties when said first single stranded nucleic acid hybridizes to a first domain of a target sequence, said second single stranded nucleic acid hybridizes to a second domain of said target sequence, and an intervening nucleic acid hybridizes to an intervening target domain of said target sequence. 
     
     
       2. A composition comprising a first single stranded nucleic acid containing one or multiple electron transfer moieties and a second single stranded nucleic acid containing one or multiple electron transfer moieties, wherein one of said electron transfer moieties is an electrode and the other is a transition metal complex covalently attached to a ribose of the ribose-phosphate backbone of said nucleic acid, wherein electron transfer occurs between said electron transfer moieties when said first single stranded nucleic acid hybridizes to a first domain of a target sequence, said second single stranded nucleic acid hybridizes to a second domain of said target sequence, and an intervening nucleic acid hybridizes to an intervening target domain of said target sequence. 
     
     
       3. A composition according to claim 1 wherein said attachment is to the 2' position of said ribose. 
     
     
       4. A composition according to claim 1 wherein said attachment is to the 3' position of said ribose. 
     
     
       5. A composition according to claim 1 wherein there are no more than 5 unconjugated sigma bonds between said transition metal and the base attached to said ribose. 
     
     
       6. A composition according to claim 1 wherein there are no more than 4 unconjugated sigma bonds between said transition metal and the base attached to said ribose. 
     
     
       7. A single stranded nucleic acid containing one or multiple electron donor moieties and one or multiple electron acceptor moieties, wherein said electron donor and acceptor moieties are transition metal complexes covalently attached to the ribose-phosphate backbone of said nucleic acid, wherein one or multiple of said transition metal complexes is covalently attached via a modified nucleotide dimer, and wherein electron transfer can occur between said electron donor and acceptor moieties when said single stranded nucleic acid is hybridized to a target sequence. 
     
     
       8. A single stranded nucleic acid containing one or multiple electron donor moieties and one or multiple electron acceptor moieties, wherein one of said electron transfer moieties is an electrode and the other is a transition metal complex covalently attached via a modified nucleotide dimer, and wherein electron transfer can occur between said electron donor and acceptor moieties when said single stranded nucleic acid is hybridized to a target sequence. 
     
     
       9. A single stranded nucleic acid according to claim 7 or 8, wherein said modified nucleotide dimer contains a phosphoramide linkage. 
     
     
       10. A single stranded nucleic acid according to claim 7 wherein one or multiple of said transition metal complexes is covalently attached via a ribose of the ribose-phosphate backbone. 
     
     
       11. A composition comprising a first single stranded nucleic acid containing one or multiple electron transfer moieties and a second single stranded nucleic acid containing one or multiple electron transfer moieties, wherein each of said electron transfer moieties is a transition metal complex covalently attached to a ribose of the ribose-phosphate backbone of said first and second single stranded nucleic acids, and wherein electron transfer occurs between said electron transfer moieties when said first single stranded nucleic acid is hybridized to said second single stranded nucleic acid. 
     
     
       12. A composition comprising a first single stranded nucleic acid containing one or multiple electron transfer moieties and a second single stranded nucleic acid containing one or multiple electron transfer moieties, wherein one of said electron transfer moieties is an electrode and the other is a transition metal complex covalently attached to the ribose-phosphate backbone of said nucleic acid, and wherein electron transfer occurs between said electron transfer moieties when said first single stranded nucleic acid is hybridized to said second single stranded nucleic acid. 
     
     
       13. A method of making a single stranded nucleic acid containing one or multiple electron donor moieties and one or multiple electron acceptor moieties, wherein said electron donor and acceptor moieties are transition metal complexes covalently attached to the ribose-phosphate backbone of said nucleic acid, wherein electron transfer can occur between said electron donor and acceptor moieties when said single stranded nucleic acid is hybridized to a target sequence, said method comprising a) incorporating a modified nucleotide to form a modified single stranded nucleic acid.   
     
     
       14. A method according to claim 13 further comprising b) hybridizing said modified nucleic acid with a complementary single stranded nucleic acid to form a double stranded nucleic acid.   
     
     
       15. A method according to claim 13 or 14 further comprising c) reacting said modified nucleotide with an electron transfer moiety such that said moiety is covalently attached to said modified nucleotide.   
     
     
       16. A method according to claim 13 wherein said modified nucleotide is an amino-modified nucleotide. 
     
     
       17. A method according to claim 16 wherein said amino-modified nucleotide is a 2' amino modified nucleotide. 
     
     
       18. A method according to claim 16 wherein said amino-modified nucleotide is a 3' amino modified nucleotide. 
     
     
       19. A method according to claim 13 wherein said modified nucleotide is a modified nucleotide dimer. 
     
     
       20. A method according to claim 13 wherein said incorporation is via standard synthetic techniques. 
     
     
       21. A method according to claim 13 wherein said incorporation is via enzymatic addition.